This blog provides stories that Denyse O'Leary, a Toronto-based journalist, has found to be of interest, as she covers the growing intelligent design controversy. It supports her book By Design or by Chance? (Augsburg 2004). Does the universe - and do life forms - show evidence of intelligent design? If so, Carl Sagan was wrong and so is Richard Dawkins. Now what?

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Sunday, July 19, 2009

Extinction: A 62-million-year itch?

At Seed Magazine (June 29, 2009), Adrian Melott of "The Big Idea" asks, "Sometimes, something kills nearly all life on the entire planet. But is there a regular cycle to this creation and destruction of Earth’s biodiversity?", arguing,

Fortunately, all known dips in biodiversity seem to be followed by periods of rapid diversification called radiations. It was the end-Permian event that allowed the dinosaurs to develop and flourish. Of course, yet another mass extinction ended their reign. In their place, birds and then mammals ascended. And now humans have emerged. But even with all our intelligence and technology, we still don’t really understand what causes extinctions or radiations.

One of the big mysteries associated with these phenomena is also a key question for life’s future: Do they occur with any regularity? If we discovered a cycle to these events, it might suggest what’s driving the changes on Earth, and what linkage, if any, they have to events elsewhere in the universe.

He plays with the idea of a 62-million-year cycle:

Soon I was losing sleep over something I’d read in a 2005 issue of Nature. Robert Rohde and his mentor, Richard Muller of UC Berkeley, had reported a fascinating cycle in biodiversity within a major compendium of fossil data sets, a regular 62-million-year rise and fall in the count of all kinds of creatures. They had explored several mechanisms to explain it and found them lacking, but both they and their editors deemed the signal so significant that it was published.